SMA SUNNY BOY 1300TL - Red LED Is Glowing Continuously; Checking the PV Array for a Ground Fault

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52 SB13_21TL-IA-IEN121060 Installation Guide
9.3 Red LED is Glowing Continuously
If the red status display LED lights up continuously during operation, there is a ground fault in the PV
array, at least one varistor for overvoltage protection is defective or there is an insulation fault.
Procedure
1. Check for ground faults in the PV array as described in section 9.3.1"Checking the PV Array
for a Ground Fault" (page52).
2. If the red LED continues to glow, check the varistors as described in section 9.3.2"Checking the
Function of the Varistors" (page54).
9.3.1 Checking the PV Array for a Ground Fault
1. Disconnect the inverter from both the DC and AC connections as described in section
7.2"Opening the Inverter" (page39).
2. Measure the voltages between the plus pole of
each string and the ground potential (PE).
3. Measure the voltages between the minus pole of
each string and the ground potential (PE).
DANGER!
Risk of lethal electric shock.
• Only touch the cables of the PV array on their insulation.
• Do not connect strings with ground faults to the inverter.
NOTICE!
Excessive voltages can destroy the measuring device.
• Use only measuring devices with a DC input voltage range up to at least 1 000 V.